The following relates generally to wireless communication, and more specifically to tracking reference signal (TRS) for New Radio (NR).
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system, or an NR system. A wireless multiple-access communications system may include a number of base stations or access network nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
In some wireless communications systems, base stations may transmit synchronization signals and reference signals over a carrier to assist UEs with cell acquisition as well as frequency and time tracking of the carrier. For example, synchronization signals may allow UEs to detect a cell transmitted over a carrier. Synchronization signals may also allow the UEs to detect the center frequency of the carrier and achieve synchronization at the transmission time interval or symbol level. However, for robust reception and demodulation across a system bandwidth, the UEs may also maintain tracking loops using reference signals that span a larger portion of the system bandwidth.
Some base stations may continuously transmit reference signals such as cell reference signals (CRS) within a subset of resources of each resource block across the system bandwidth. Continuous transmission of reference signals may draw significant power and in some cases may be an unnecessary waste of resources, particularly when no UEs are connected to or tracking timing for a cell associated with the base station. Furthermore, UE power consumption may increase as the relative amount of time that the UE is receiving reference signal transmissions increases. In addition, communication with UEs may experience latency as tracking loops converge. Thus, supporting robust time tracking for cells that intermittently serve UEs may provide challenges in power management at both base stations and UEs.